/*
 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.lang.invoke;

import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Field;

import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

/**
 * The JVM interface for the method handles package is all here.
 * This is an interface internal and private to an implementation of JSR 292.
 * <em>This class is not part of the JSR 292 standard.</em>
 *
 * @author jrose
 */
class MethodHandleNatives {

  private MethodHandleNatives() {
  } // static only

  /// MemberName support

  static native void init(MemberName self, Object ref);

  static native void expand(MemberName self);

  static native MemberName resolve(MemberName self, Class<?> caller) throws LinkageError;

  static native int getMembers(Class<?> defc, String matchName, String matchSig,
      int matchFlags, Class<?> caller, int skip, MemberName[] results);

  /// Field layout queries parallel to sun.misc.Unsafe:
  static native long objectFieldOffset(MemberName self);  // e.g., returns vmindex

  static native long staticFieldOffset(MemberName self);  // e.g., returns vmindex

  static native Object staticFieldBase(MemberName self);  // e.g., returns clazz

  static native Object getMemberVMInfo(MemberName self);  // returns {vmindex,vmtarget}

  /// MethodHandle support

  /**
   * Fetch MH-related JVM parameter.
   * which=0 retrieves MethodHandlePushLimit
   * which=1 retrieves stack slot push size (in address units)
   */
  static native int getConstant(int which);

  static final boolean COUNT_GWT;

  /// CallSite support

  /**
   * Tell the JVM that we need to change the target of a CallSite.
   */
  static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);

  static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);

  private static native void registerNatives();

  static {
    registerNatives();
    COUNT_GWT = getConstant(Constants.GC_COUNT_GWT) != 0;

    // The JVM calls MethodHandleNatives.<clinit>.  Cascade the <clinit> calls as needed:
    MethodHandleImpl.initStatics();
  }

  // All compile-time constants go here.
  // There is an opportunity to check them against the JVM's idea of them.
  static class Constants {

    Constants() {
    } // static only

    // MethodHandleImpl
    static final int // for getConstant
        GC_COUNT_GWT = 4,
        GC_LAMBDA_SUPPORT = 5;

    // MemberName
    // The JVM uses values of -2 and above for vtable indexes.
    // Field values are simple positive offsets.
    // Ref: src/share/vm/oops/methodOop.hpp
    // This value is negative enough to avoid such numbers,
    // but not too negative.
    static final int
        MN_IS_METHOD = 0x00010000, // method (not constructor)
        MN_IS_CONSTRUCTOR = 0x00020000, // constructor
        MN_IS_FIELD = 0x00040000, // field
        MN_IS_TYPE = 0x00080000, // nested type
        MN_CALLER_SENSITIVE = 0x00100000, // @CallerSensitive annotation detected
        MN_REFERENCE_KIND_SHIFT = 24, // refKind
        MN_REFERENCE_KIND_MASK = 0x0F000000 >> MN_REFERENCE_KIND_SHIFT,
    // The SEARCH_* bits are not for MN.flags but for the matchFlags argument of MHN.getMembers:
    MN_SEARCH_SUPERCLASSES = 0x00100000,
        MN_SEARCH_INTERFACES = 0x00200000;

    /**
     * Basic types as encoded in the JVM.  These code values are not
     * intended for use outside this class.  They are used as part of
     * a private interface between the JVM and this class.
     */
    static final int
        T_BOOLEAN = 4,
        T_CHAR = 5,
        T_FLOAT = 6,
        T_DOUBLE = 7,
        T_BYTE = 8,
        T_SHORT = 9,
        T_INT = 10,
        T_LONG = 11,
        T_OBJECT = 12,
    //T_ARRAY    = 13
    T_VOID = 14,
    //T_ADDRESS  = 15
    T_ILLEGAL = 99;

    /**
     * Constant pool entry types.
     */
    static final byte
        CONSTANT_Utf8 = 1,
        CONSTANT_Integer = 3,
        CONSTANT_Float = 4,
        CONSTANT_Long = 5,
        CONSTANT_Double = 6,
        CONSTANT_Class = 7,
        CONSTANT_String = 8,
        CONSTANT_Fieldref = 9,
        CONSTANT_Methodref = 10,
        CONSTANT_InterfaceMethodref = 11,
        CONSTANT_NameAndType = 12,
        CONSTANT_MethodHandle = 15,  // JSR 292
        CONSTANT_MethodType = 16,  // JSR 292
        CONSTANT_InvokeDynamic = 18,
        CONSTANT_LIMIT = 19;   // Limit to tags found in classfiles

    /**
     * Access modifier flags.
     */
    static final char
        ACC_PUBLIC = 0x0001,
        ACC_PRIVATE = 0x0002,
        ACC_PROTECTED = 0x0004,
        ACC_STATIC = 0x0008,
        ACC_FINAL = 0x0010,
        ACC_SYNCHRONIZED = 0x0020,
        ACC_VOLATILE = 0x0040,
        ACC_TRANSIENT = 0x0080,
        ACC_NATIVE = 0x0100,
        ACC_INTERFACE = 0x0200,
        ACC_ABSTRACT = 0x0400,
        ACC_STRICT = 0x0800,
        ACC_SYNTHETIC = 0x1000,
        ACC_ANNOTATION = 0x2000,
        ACC_ENUM = 0x4000,
    // aliases:
    ACC_SUPER = ACC_SYNCHRONIZED,
        ACC_BRIDGE = ACC_VOLATILE,
        ACC_VARARGS = ACC_TRANSIENT;

    /**
     * Constant pool reference-kind codes, as used by CONSTANT_MethodHandle CP entries.
     */
    static final byte
        REF_NONE = 0,  // null value
        REF_getField = 1,
        REF_getStatic = 2,
        REF_putField = 3,
        REF_putStatic = 4,
        REF_invokeVirtual = 5,
        REF_invokeStatic = 6,
        REF_invokeSpecial = 7,
        REF_newInvokeSpecial = 8,
        REF_invokeInterface = 9,
        REF_LIMIT = 10;
  }

  static boolean refKindIsValid(int refKind) {
    return (refKind > REF_NONE && refKind < REF_LIMIT);
  }

  static boolean refKindIsField(byte refKind) {
    assert (refKindIsValid(refKind));
    return (refKind <= REF_putStatic);
  }

  static boolean refKindIsGetter(byte refKind) {
    assert (refKindIsValid(refKind));
    return (refKind <= REF_getStatic);
  }

  static boolean refKindIsSetter(byte refKind) {
    return refKindIsField(refKind) && !refKindIsGetter(refKind);
  }

  static boolean refKindIsMethod(byte refKind) {
    return !refKindIsField(refKind) && (refKind != REF_newInvokeSpecial);
  }

  static boolean refKindIsConstructor(byte refKind) {
    return (refKind == REF_newInvokeSpecial);
  }

  static boolean refKindHasReceiver(byte refKind) {
    assert (refKindIsValid(refKind));
    return (refKind & 1) != 0;
  }

  static boolean refKindIsStatic(byte refKind) {
    return !refKindHasReceiver(refKind) && (refKind != REF_newInvokeSpecial);
  }

  static boolean refKindDoesDispatch(byte refKind) {
    assert (refKindIsValid(refKind));
    return (refKind == REF_invokeVirtual ||
        refKind == REF_invokeInterface);
  }

  static {
    final int HR_MASK = ((1 << REF_getField) |
        (1 << REF_putField) |
        (1 << REF_invokeVirtual) |
        (1 << REF_invokeSpecial) |
        (1 << REF_invokeInterface)
    );
    for (byte refKind = REF_NONE + 1; refKind < REF_LIMIT; refKind++) {
      assert (refKindHasReceiver(refKind) == (((1 << refKind) & HR_MASK) != 0)) : refKind;
    }
  }

  static String refKindName(byte refKind) {
    assert (refKindIsValid(refKind));
    switch (refKind) {
      case REF_getField:
        return "getField";
      case REF_getStatic:
        return "getStatic";
      case REF_putField:
        return "putField";
      case REF_putStatic:
        return "putStatic";
      case REF_invokeVirtual:
        return "invokeVirtual";
      case REF_invokeStatic:
        return "invokeStatic";
      case REF_invokeSpecial:
        return "invokeSpecial";
      case REF_newInvokeSpecial:
        return "newInvokeSpecial";
      case REF_invokeInterface:
        return "invokeInterface";
      default:
        return "REF_???";
    }
  }

  private static native int getNamedCon(int which, Object[] name);

  static boolean verifyConstants() {
    Object[] box = {null};
    for (int i = 0; ; i++) {
      box[0] = null;
      int vmval = getNamedCon(i, box);
      if (box[0] == null) {
        break;
      }
      String name = (String) box[0];
      try {
        Field con = Constants.class.getDeclaredField(name);
        int jval = con.getInt(null);
        if (jval == vmval) {
          continue;
        }
        String err = (name + ": JVM has " + vmval + " while Java has " + jval);
        if (name.equals("CONV_OP_LIMIT")) {
          System.err.println("warning: " + err);
          continue;
        }
        throw new InternalError(err);
      } catch (NoSuchFieldException | IllegalAccessException ex) {
        String err = (name + ": JVM has " + vmval + " which Java does not define");
        // ignore exotic ops the JVM cares about; we just wont issue them
        //System.err.println("warning: "+err);
        continue;
      }
    }
    return true;
  }

  static {
    assert (verifyConstants());
  }

  // Up-calls from the JVM.
  // These must NOT be public.

  /**
   * The JVM is linking an invokedynamic instruction.  Create a reified call site for it.
   */
  static MemberName linkCallSite(Object callerObj,
      Object bootstrapMethodObj,
      Object nameObj, Object typeObj,
      Object staticArguments,
      Object[] appendixResult) {
    MethodHandle bootstrapMethod = (MethodHandle) bootstrapMethodObj;
    Class<?> caller = (Class<?>) callerObj;
    String name = nameObj.toString().intern();
    MethodType type = (MethodType) typeObj;
    if (!TRACE_METHOD_LINKAGE) {
      return linkCallSiteImpl(caller, bootstrapMethod, name, type,
          staticArguments, appendixResult);
    }
    return linkCallSiteTracing(caller, bootstrapMethod, name, type,
        staticArguments, appendixResult);
  }

  static MemberName linkCallSiteImpl(Class<?> caller,
      MethodHandle bootstrapMethod,
      String name, MethodType type,
      Object staticArguments,
      Object[] appendixResult) {
    CallSite callSite = CallSite.makeSite(bootstrapMethod,
        name,
        type,
        staticArguments,
        caller);
    if (callSite instanceof ConstantCallSite) {
      appendixResult[0] = callSite.dynamicInvoker();
      return Invokers.linkToTargetMethod(type);
    } else {
      appendixResult[0] = callSite;
      return Invokers.linkToCallSiteMethod(type);
    }
  }

  // Tracing logic:
  static MemberName linkCallSiteTracing(Class<?> caller,
      MethodHandle bootstrapMethod,
      String name, MethodType type,
      Object staticArguments,
      Object[] appendixResult) {
    Object bsmReference = bootstrapMethod.internalMemberName();
    if (bsmReference == null) {
      bsmReference = bootstrapMethod;
    }
    Object staticArglist = (staticArguments instanceof Object[] ?
        java.util.Arrays.asList((Object[]) staticArguments) :
        staticArguments);
    System.out.println("linkCallSite " + caller.getName() + " " +
        bsmReference + " " +
        name + type + "/" + staticArglist);
    try {
      MemberName res = linkCallSiteImpl(caller, bootstrapMethod, name, type,
          staticArguments, appendixResult);
      System.out.println("linkCallSite => " + res + " + " + appendixResult[0]);
      return res;
    } catch (Throwable ex) {
      System.out.println("linkCallSite => throw " + ex);
      throw ex;
    }
  }

  /**
   * The JVM wants a pointer to a MethodType.  Oblige it by finding or creating one.
   */
  static MethodType findMethodHandleType(Class<?> rtype, Class<?>[] ptypes) {
    return MethodType.makeImpl(rtype, ptypes, true);
  }

  /**
   * The JVM wants to link a call site that requires a dynamic type check.
   * Name is a type-checking invoker, invokeExact or invoke.
   * Return a JVM method (MemberName) to handle the invoking.
   * The method assumes the following arguments on the stack:
   * 0: the method handle being invoked
   * 1-N: the arguments to the method handle invocation
   * N+1: an optional, implicitly added argument (typically the given MethodType)
   * <p>
   * The nominal method at such a call site is an instance of
   * a signature-polymorphic method (see @PolymorphicSignature).
   * Such method instances are user-visible entities which are
   * "split" from the generic placeholder method in {@code MethodHandle}.
   * (Note that the placeholder method is not identical with any of
   * its instances.  If invoked reflectively, is guaranteed to throw an
   * {@code UnsupportedOperationException}.)
   * If the signature-polymorphic method instance is ever reified,
   * it appears as a "copy" of the original placeholder
   * (a native final member of {@code MethodHandle}) except
   * that its type descriptor has shape required by the instance,
   * and the method instance is <em>not</em> varargs.
   * The method instance is also marked synthetic, since the
   * method (by definition) does not appear in Java source code.
   * <p>
   * The JVM is allowed to reify this method as instance metadata.
   * For example, {@code invokeBasic} is always reified.
   * But the JVM may instead call {@code linkMethod}.
   * If the result is an * ordered pair of a {@code (method, appendix)},
   * the method gets all the arguments (0..N inclusive)
   * plus the appendix (N+1), and uses the appendix to complete the call.
   * In this way, one reusable method (called a "linker method")
   * can perform the function of any number of polymorphic instance
   * methods.
   * <p>
   * Linker methods are allowed to be weakly typed, with any or
   * all references rewritten to {@code Object} and any primitives
   * (except {@code long}/{@code float}/{@code double})
   * rewritten to {@code int}.
   * A linker method is trusted to return a strongly typed result,
   * according to the specific method type descriptor of the
   * signature-polymorphic instance it is emulating.
   * This can involve (as necessary) a dynamic check using
   * data extracted from the appendix argument.
   * <p>
   * The JVM does not inspect the appendix, other than to pass
   * it verbatim to the linker method at every call.
   * This means that the JDK runtime has wide latitude
   * for choosing the shape of each linker method and its
   * corresponding appendix.
   * Linker methods should be generated from {@code LambdaForm}s
   * so that they do not become visible on stack traces.
   * <p>
   * The {@code linkMethod} call is free to omit the appendix
   * (returning null) and instead emulate the required function
   * completely in the linker method.
   * As a corner case, if N==255, no appendix is possible.
   * In this case, the method returned must be custom-generated to
   * to perform any needed type checking.
   * <p>
   * If the JVM does not reify a method at a call site, but instead
   * calls {@code linkMethod}, the corresponding call represented
   * in the bytecodes may mention a valid method which is not
   * representable with a {@code MemberName}.
   * Therefore, use cases for {@code linkMethod} tend to correspond to
   * special cases in reflective code such as {@code findVirtual}
   * or {@code revealDirect}.
   */
  static MemberName linkMethod(Class<?> callerClass, int refKind,
      Class<?> defc, String name, Object type,
      Object[] appendixResult) {
    if (!TRACE_METHOD_LINKAGE) {
      return linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
    }
    return linkMethodTracing(callerClass, refKind, defc, name, type, appendixResult);
  }

  static MemberName linkMethodImpl(Class<?> callerClass, int refKind,
      Class<?> defc, String name, Object type,
      Object[] appendixResult) {
    try {
      if (defc == MethodHandle.class && refKind == REF_invokeVirtual) {
        return Invokers
            .methodHandleInvokeLinkerMethod(name, fixMethodType(callerClass, type), appendixResult);
      }
    } catch (Throwable ex) {
      if (ex instanceof LinkageError) {
        throw (LinkageError) ex;
      } else {
        throw new LinkageError(ex.getMessage(), ex);
      }
    }
    throw new LinkageError("no such method " + defc.getName() + "." + name + type);
  }

  private static MethodType fixMethodType(Class<?> callerClass, Object type) {
    if (type instanceof MethodType) {
      return (MethodType) type;
    } else {
      return MethodType.fromMethodDescriptorString((String) type, callerClass.getClassLoader());
    }
  }

  // Tracing logic:
  static MemberName linkMethodTracing(Class<?> callerClass, int refKind,
      Class<?> defc, String name, Object type,
      Object[] appendixResult) {
    System.out.println("linkMethod " + defc.getName() + "." +
        name + type + "/" + Integer.toHexString(refKind));
    try {
      MemberName res = linkMethodImpl(callerClass, refKind, defc, name, type, appendixResult);
      System.out.println("linkMethod => " + res + " + " + appendixResult[0]);
      return res;
    } catch (Throwable ex) {
      System.out.println("linkMethod => throw " + ex);
      throw ex;
    }
  }


  /**
   * The JVM is resolving a CONSTANT_MethodHandle CP entry.  And it wants our help.
   * It will make an up-call to this method.  (Do not change the name or signature.)
   * The type argument is a Class for field requests and a MethodType for non-fields.
   * <p>
   * Recent versions of the JVM may also pass a resolved MemberName for the type.
   * In that case, the name is ignored and may be null.
   */
  static MethodHandle linkMethodHandleConstant(Class<?> callerClass, int refKind,
      Class<?> defc, String name, Object type) {
    try {
      Lookup lookup = IMPL_LOOKUP.in(callerClass);
      assert (refKindIsValid(refKind));
      return lookup.linkMethodHandleConstant((byte) refKind, defc, name, type);
    } catch (IllegalAccessException ex) {
      Throwable cause = ex.getCause();
      if (cause instanceof AbstractMethodError) {
        throw (AbstractMethodError) cause;
      } else {
        Error err = new IllegalAccessError(ex.getMessage());
        throw initCauseFrom(err, ex);
      }
    } catch (NoSuchMethodException ex) {
      Error err = new NoSuchMethodError(ex.getMessage());
      throw initCauseFrom(err, ex);
    } catch (NoSuchFieldException ex) {
      Error err = new NoSuchFieldError(ex.getMessage());
      throw initCauseFrom(err, ex);
    } catch (ReflectiveOperationException ex) {
      Error err = new IncompatibleClassChangeError();
      throw initCauseFrom(err, ex);
    }
  }

  /**
   * Use best possible cause for err.initCause(), substituting the
   * cause for err itself if the cause has the same (or better) type.
   */
  static private Error initCauseFrom(Error err, Exception ex) {
    Throwable th = ex.getCause();
    if (err.getClass().isInstance(th)) {
      return (Error) th;
    }
    err.initCause(th == null ? ex : th);
    return err;
  }

  /**
   * Is this method a caller-sensitive method?
   * I.e., does it call Reflection.getCallerClass or a similer method
   * to ask about the identity of its caller?
   */
  static boolean isCallerSensitive(MemberName mem) {
    if (!mem.isInvocable()) {
      return false;  // fields are not caller sensitive
    }

    return mem.isCallerSensitive() || canBeCalledVirtual(mem);
  }

  static boolean canBeCalledVirtual(MemberName mem) {
    assert (mem.isInvocable());
    Class<?> defc = mem.getDeclaringClass();
    switch (mem.getName()) {
      case "checkMemberAccess":
        return canBeCalledVirtual(mem, java.lang.SecurityManager.class);
      case "getContextClassLoader":
        return canBeCalledVirtual(mem, java.lang.Thread.class);
    }
    return false;
  }

  static boolean canBeCalledVirtual(MemberName symbolicRef, Class<?> definingClass) {
    Class<?> symbolicRefClass = symbolicRef.getDeclaringClass();
    if (symbolicRefClass == definingClass) {
      return true;
    }
    if (symbolicRef.isStatic() || symbolicRef.isPrivate()) {
      return false;
    }
    return (definingClass.isAssignableFrom(symbolicRefClass) ||  // Msym overrides Mdef
        symbolicRefClass.isInterface());                     // Mdef implements Msym
  }
}
